On Jul 5, 11:26*am, Tim Streater wrote:
In article ,
*The Natural Philosopher wrote:



Huge wrote:
On 2010-07-05, Tim Watts wrote:
Huge
* wibbled on Monday 05 July 2010 10:32

On 2010-07-05, Tim Watts wrote:

I was talking to an air-con engineer last Saturday. He was saying that,
according to the contact he's had with manufacturers and various
seminars, that the big push is to get air source pumps into a viable
state as it is well recognised that ground source is too expensive
and/or difficult for the majority to adopt.

Apparently, they have air source producing useful output at air
temperatures slightly below freezing and producing useful temperatures
on the output side, so as always the effort is to make it viable
commercially.

It sounded potentially quite promising. Not sure if it's going to be a
matter of years or a decade, but watch this space...
Given that air source heat pumps are routinely installed in the USA, I
don't really understand what the issue is.

Which bits of the USA though? Cold northern areas or generally warmer
southern climes?

Good point. I only have direct experience of my Mother's house, which was
(she *now lives in a retirement community) in Pennsylvania. Much colder
than the *UK in the winter and much, much hotter in the summer. The heat
pump ran both the heating and air-con. All the houses on the estate she
lived on had them - the only energy source was electricity. When it was
substantially below freezing, she had to switch to pure resistive heating
, since the heat pump would ice up.

Aye, and there's the rub.

Air source is supposed to be OK down to a few deg.

Ground source is far more useful as teh overall land temperature varies
less.

There is a limit to what you can take out as the heat you remove from
the ground (in winter) is replenished by conduction from adjacent ground
(it's not geothermal).

Why did you snip "pumping heat into it in summer using the system as
aircon"?

MBQ